The P4' Peptide-Carrying in Cottonseed Meal Improves the Chinese Mitten Crab Innate Immunity, Redox Defense, and Growth Performance.

This study developed a recombinant to carry the LGSPDVIVIR peptide (cmP4) isolated from the hydrolyzed products of cottonseed meal with excellent antioxidant and immune-enhancing properties in vitro. It was carried as a tandem of five cmP4 peptides (cmP4') to be stably expressed on a large scale. Then, its effectiveness was evaluated in Chinese mitten crab () based on growth performance, redox defense, and innate immunity. A total of 280 crabs (mean body weight: 41.40 ± 0.14) were randomly assigned to seven diets including a control one (without ) and six experimental ones with different doses (10,10, and 10 CFU/kg) of unmodified and recombinant , respectively, for 12 weeks. Each diet was tested in four tanks of crabs (10/tank). In terms of bacterial dosages, the final weight (FW), weight gain (WG), hemolymph and hepatopancreatic activities of superoxide dismutase (SOD), catalase (CAT), lysosome (LZM), acid phosphatase (ACP) and alkaline phosphatase (AKP), and hepatopancreatic transcriptions of , mitochondrial manganese superoxide dismutase (), thioredoxin-1 (), and prophenoloxidase () all increased significantly with increasing dosages, while hemolymph and hepatopancreatic malondialdehyde (MDA) content and the transcriptions of toll like receptors (), NF-B-like transcription factor (), and lipopolysaccharide-induced TNF- factor () all decreased remarkably. In terms of bacterial species, the recombinant group obtained significantly high values of FW, WG, hemolymph, and hepatopancreatic activities of SOD, CAT, LZM, ACP, and AKP, and the transcriptions of , peroxiredoxin 6 (), and compared with the unmodified , while opposite results were noted in hemolymph and hepatopancreatic MDA content and the transcriptions of , , and . These results indicated that dietary supplementation with 10 CFU/kg of recombinant can improve the growth performance, redox defense, and nonspecific immunity of .